1. Field of the Invention
The present invention relates generally to shock absorbers having a specialized rebound valve. More particularly, the present invention relates to a shock absorber having a rebound valve defined by a flexing disc assembly that combines both the flexing disc function of normal valving with a blow-off function.
2. Description of the Relevant Art
Shock absorbers are used in connection with automobile suspension systems and other vehicle suspension systems to absorb unwanted vibrations which occur during locomotion. To absorb this unwanted vibration, shock absorbers are generally connected between the body and the suspension of the automobile.
The most common type of shock absorber in automobiles is the dashpot type in which a piston is located within the shock absorber and is connected to the vehicle body through a piston rod. Because the piston is available to limit the flow of damping fluid within the working chamber of the shock absorber when the shock absorber is compressed or extended, the shock absorber is able to produce a damping force which counteracts the vibration which would otherwise be transmitted from the suspension of the automobile to the body.
A conventional shock absorber comprises a pressure tube with a piston therein. A piston rod connected to the piston projects from one end of the pressure tube. Damping is controlled by orifices in the piston which regulate passage of fluid from one side of the piston to the other.
Vehicle shock absorbers are generally provided with bleed orifices which allow the restricted flow of damping fluid between the rebound side and the compression side. It is essentially this bleeding that provides the shock absorber with its damping characteristics.
Furthermore, shock absorbers include a blow off valve of some type. These valves are normally in a closed position. However, when pressure within the cylinder achieves a certain predetermined point, the blow off valve opens and alters considerably the restriction of damping fluid flow that would otherwise occur without the presence of the blow off valve.
Conventional shock absorbers utilize relatively complex structures to provide the bleed orifice and the blow off valve. For example, U.S. Pat. No. 4,721,130, issued on Jan. 26, 1988, to Hayashi for VALVE STRUCTURE OF HYDRAULIC BUFFER discloses a valve structure used in a hydraulic buffer. A valve body is used for opening and closing ports in the piston. As the piston rod is extended, a free end of the valve body deflects about a first fulcrum to allow liquid to pass. When the piston is moving at a high speed and the force of liquid passing through the port exceeds the pre-load set to the spring, the spring seat is depressed so that more liquid flows through the port while deflecting the valve body about a second fulcrum.
Additionally, U.S. Pat. No. 2,717,058, issued to Brundrett on Sep. 6, 1955, for SHOCK ABSORBER CONTROL VALVE discloses a shock absorber control valve for controlling restricted flow of hydraulic fluid between opposite ends of a shock absorber cylinder. A valve disk flexes upwardly against a rigid retainer plate as permitted by the angularity of the face portion of the plate. As the requirement for flow further increases, the valve member and the retainer are moved against the compression spring to change the fluid flow rate.
While providing advancements in the art of shock absorber valving, these inventions are relatively complex and fail to produce satisfactory results in terms of efficiency and cost. Accordingly, a shock absorber that combines the flexing disc function of a rebound valve with the blow off function is wanting.